There are a variety of vehicle brakes adapted to slow down, stop, and keep railway vehicles or cars stopped. A caliper brake (disc brake) assembly that applies frictional force while held between discs rotating with wheels is now adopted as a brake structure for railway vehicles.
This caliper brake is broken down into two types: hydraulic braking and pneumatic braking. So far, hydraulic braking has been used primarily for the high-speed Shinkansen or Bullet Train; however, recent demands for reductions in the weight of vehicles have led to mounting demands for the adoption of pneumatic braking regardless of the old railway line or the Shinkansen.
Such a pneumatic braking type caliper brake assembly usually includes an actuator that displaces a brake pad toward or away from discs. Used for that actuator is a diaphragm for transmitting pressure to pistons, which diaphragm is operable to press the brake pad against the discs via various members or parts. Prior arts relevant to brake assemblies include JP(A) 2009-92194 as an example.
The diaphragm used with such a caliper brake is required not only to withstand frictionally generated heat and repetitive operations but also to have cold resistance good enough to stand up to cold-area specifications. Referring especially to the diaphragm used as an actuator that operates as a vitally important part of braking, there is still a great demand for a vehicle brake-specific diaphragm that has much better durability, although there is no end to improvements in such a variety of durability requirements as described above. Prior arts relevant to the present invention, for instance, include JP(A)'s 2004-197260 and 2004-281834, although there is no explicit reference to brake-specific diaphragms.
The situations being like this, the present invention has for its object to provide a diaphragm for vehicle brakes (floating caliper brakes) that does not only have durability during operation in both high-temperature and normal-temperature areas but also exerts much better durability during operation in a low-temperature area.